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Early Vλ diversification in sheep
Author(s) -
Jeong Youngkee,
Osborne Barbara A.,
Goldsby Richard A.
Publication year - 2001
Publication title -
immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.297
H-Index - 133
eISSN - 1365-2567
pISSN - 0019-2805
DOI - 10.1046/j.1365-2567.2001.01227.x
Subject(s) - biology , spleen , repertoire , germline , antibody , gene , complementary dna , microbiology and biotechnology , immunology , genetics , physics , acoustics
Summary This study examined a number of tissues during early gestation in foetal sheep to determine the earliest site of Vλ expression and time of generation of the Vλ repertoire. Tissues, including spleen, liver, gut, blood and bone marrow, were obtained from 48, 55, 60 and 63 gestational day (g.d.) ovine foetuses and cDNA libraries were prepared from them by reverse transcription–polymerase chain reaction. Clones were randomly selected from cDNA libraries and subjected to sequencing. Analysis of these sequences and comparison with a pool of germline genes led to the following conclusions. The expression of Vλ occurs earlier in spleen (48 g.d.) than in all of the other tissues examined. Also, diversity is seen earlier and at higher levels in early foetal spleen than in all of the other tissues examined. In this regard, it is notable that splenic Vλ expression is readily apparent even before such gut‐associated lymphoid tissue as the ileal Peyer's patch (IPP) has developed. Two germline Vλ genes, 5.1 and 5.3 predominate in early immunoglobulin λ light‐chain gene rearrangement. Examination of Jλ usage revealed the existence of a new Jλ gene and its utilization during the early phases of the development of the ovine antibody repertoire. This study indicates that sites other than the IPP contribute to the diversification of the Vλ repertoire in sheep. We suggest that it is likely that foetal spleen may provide a partially diversified B‐cell repertoire before the IPP becomes active as a major site for massive clonal expansion and extensive diversification of B cells.